just to clarify.
while bubblenests can indicate a certain degree of happiness, not all bettas make them. even if well kept. it is a breeding instinct, something for them to do when they feel the "urge". breaking them up by doing water changes, etc., will not make them upset or sulky...they will happily build you another one if they have the urge to do so. younger bettas (ime) seem to do it more than an "old man" who oculdnt be bothered.
so if you are uncertain that your fish is happy because he hasnt built a nest, or you "destroyed" his nest, dont be. some do it all the time, some a few times, some irregulary and some not at all. just so y'all are informed.
cheers!